The invention relates to a method for classifying vehicles passing a predetermined waypoint on a road.
It is necessary for military reconnaissance to detect in a timely fashion and reliably analyze the movements of troop units in an assembly area. For this purpose, the observation of vehicle movements along specific road segments is indispensable for determining not only the number but also the type of vehicles passing a waypoint.
U.S. Pat. 4,158,832 discloses a known method for classifying vehicles passing a predetermined waypoint in which a seismic detector buried in the ground near the monitored road segment is used to distinguish between tracked vehicles, such as tanks or the like, and wheeled vehicles, such as semitrailer trucks, motor trucks and the like. The driving and engine noises generated by the vehicles are absorbed into the ground and propagate in the ground as seismic or solid-borne sound waves. These solid-borne sound waves are received by the seismic detector, which is preferably embodied as a geophone. With the aid of suitable signal-processing methods, criteria are obtained from the output signals of the geophone that permit the identification of the received solid-borne sound waves as being emitted from a tracked or a wheeled vehicle.
Such a seismic detection and classification method allows the distinction of certain generic types of vehicles, such as wheeled and tracked vehicles, from one another. However, a distinction cannot be made between specific vehicle types within a generic type, such as between heavy, multiple-axle semitrailer trucks and lighter trucks having one or several driving axles, or between tanks and lighter, likewise tracked, patrol vehicles.